Prefabricated elements of various types are known in the prior art which present disadvantages of different natures, as for instance the U.K. Pat. Ser. No. 1,456,645 in the name of NIEVES with the title "CONSTRUCTING BUILDINGS USING PREFABRICATED PARTS" uses elements of different shapes. However to build one single room in this case it is necessary to employ two elements, which have to be joined at half the height of the room sidewalls and in some cases even three joining points are required. Furthermore single slabs are used to form ceilings, which method proves to be very inconvenient and expensive. The U.K. Pat. Ser. No. 913,841 in the name of HENDERSON with the title "A METHOD OF CONSTRUCTING A BUILDING FROM PRECAST CONCRETE COMPONENTS" presents basically the same inconveniences as the preceding one; the U.K. Pat. Ser. No. 1,246,369 in the name of WOOD with the title "MULTI-STOREY BUILDING ASSEMBLY FORMED WITH PRE-FABRICATED MODULES "utilizes elements with joints between two panels, wherein these panels are laterally supported by two other opposing elements; the U.K. Pat. Ser. No. 1,007,144 in the name of PATENT CONCERN N.V. with the title "IMPROVEMENTS IN OR RELATING TO BUILDINGS CONSTRUCTED OF PREFABRICATED ELEMENTS" presents all its elements in a parallelepiped box shape which presents problems and inconveniences in particular as far as the transport to the construction site is concerned; the same problems are provided by the U.K. Pat. Ser. No. 1,429,357 in the name of GORSKI with the title "IMPROVEMENTS IN OR RELATING TO BUILDINGS" which presents also only elements of parallelepiped box shape; and finally the U.K. Pat. Ser. No. 1,382,709 in the name of WEESE with the title "IMPROVEMENTS IN OR RELATING TO BUILDING SYSTEMS" uses a series of parallelogram shaped modules, which originally have a folded state and are erected only at the construction site and this fact naturally causes higher costs in labour particularly for the assembling and joining of these modulars.